chapter 4 - Tissues Flashcards
Q: What is a tissue?
A: A tissue is a group of similar cells that usually have a common embryonic origin and work together to perform specialized functions.
Q: What are the four basic types of tissues in the human body?
A: The four basic types are epithelial, connective, muscular, and nervous tissues, categorized according to their structure and function.
Q: What is histology?
A: Histology is the study of tissues.
Q: Who is a pathologist?
A: A pathologist is a doctor who examines tissues to diagnose diseases.
Q: What is the function of epithelial tissue?
A: Epithelial tissue covers surfaces, lines organs and cavities, and forms glands, enabling interaction with the environment.
Q: What is the function of connective tissue?
A: Connective tissue supports and protects the body, binds organs, stores energy as fat, and offers disease protection.
Q: What is muscular tissue made of, and what is its function?
A: Muscular tissue is made of cells that contract to produce movement and heat.
Q: What does nervous tissue do?
A: Nervous tissue senses changes and generates signals to trigger responses in muscles and glands.
Q: What is a cell junction?
A: A cell junction is a point of contact between the plasma membranes of tissue cells, allowing them to form functional units.
Q: Why are cell junctions important in tissues?
A: They allow cells to connect and work together, forming tightly joined structures in epithelial, muscle, and nerve tissues.
Q: What is the function of tight junctions?
A: Tight junctions seal cells together to prevent the leakage of substances between them.
Q: What is the role of adhering junctions?
A: Adhering junctions provide strong mechanical attachments between cells.
Help resist cell separation during muscle activity (i.e. food passing through GI tract)
Q: How do desmosomes function?
A: Additional strength to hold cells together. Prevent cells from spreading (i.e. epidermis of skin)
Q: What is the purpose of hemidesmosomes?
A: Hemidesmosomes attach cells to the basement membrane.
Q: What role do gap junctions play?
A: Gap junctions allow communication between cells by enabling the passage of ions and small molecules.
Q: How are tight junctions formed?
A: Tight junctions are created by weblike strands of transmembrane proteins that fuse the outer surfaces of adjacent cell membranes.
Q: What is the function of tight junctions?
A: They seal off pathways between cells, preventing substances from passing through and stopping cell contents from leaking into the blood and surrounding tissues.
Q: Where are tight junctions commonly found?
A: They are abundant in epithelial cells lining the stomach, intestines, and bladder, helping to maintain the integrity of these organs’ contents and prevent leaks.
Q: What is the structure of adhering junctions?
A: Adhering junctions feature a protein layer called plaque on the inside of the cell membrane, connecting to membrane proteins and cytoskeleton microfilaments.
Q: What proteins are involved in adhering junctions, and how do they function?
Adhering junctions use proteins called cadherins. These proteins extend from one cell, cross the gap between cells, and connect to cadherins on neighboring cells.
Q: What is the role of cadherins in adhering junctions?
A: Cadherins join cells together by connecting across the space between cell membranes, providing structural integrity.
Q: How do adhering junctions help epithelial tissues?
A: They form adhesive belts around epithelial cells, helping tissues resist separation during movements, such as when food passes through the intestines.
Q: What are microfilaments, and what is their role in adhering junctions?
A: Microfilaments, or actin filaments, are the thinnest filaments of the cytoskeleton, composed of the protein actin. They are involved in adhering junctions by attaching to the plaque and aiding in structural resistance.
Q: What is the structure of desmosomes?
A: Desmosomes contain a plaque (a dense layer of proteins on the inside of the plasma membrane) that attaches to membrane proteins and intermediate filaments containing keratin.
Q: How do desmosomes differ from adhering junctions in terms of cytoskeletal attachment?
A: Unlike adhering junctions, desmosomes connect to intermediate filaments (keratin) rather than microfilaments.
Q: What is the function of keratin in desmosomes?
A: Keratin filaments span the cell, connecting desmosomes on opposite sides, and enhance cell and tissue stability.
Q: Where are desmosomes commonly found, and what is their role?
A: Desmosomes are prevalent in the epidermis and cardiac muscle, where they prevent cells from separating under stress, such as during heart contractions or skin movement.
Q: How do desmosomes contribute to tissue integrity?
A: They provide mechanical strength to tissues by preventing cell separation and maintaining cellular cohesion under stress.
Q: What is the primary function of hemidesmosomes?
A: Hemidesmosomes anchor cells to the basement membrane rather than connecting adjacent cells.
Q: How do hemidesmosomes differ from desmosomes in terms of connection?
A: Unlike desmosomes, hemidesmosomes do not link adjacent cells; they instead anchor cells to the basement membrane.
Q: What transmembrane proteins are used in hemidesmosomes?
A: Hemidesmosomes use integrins as their transmembrane proteins, rather than cadherins.
Q: What role does laminin play in hemidesmosomes?
A: Laminin, a glycoprotein in the extracellular matrix, provides a structural foundation by linking with integrins to stabilize and anchor cells to the basement membrane.
Q: What are gap junctions?
A: Gap junctions are tiny fluid-filled channels that connect nearby cells, allowing ions and small molecules to pass between them.
Q: What proteins form gap junctions?
A: Gap junctions are formed by proteins called connexins.
Q: What is the key function of gap junctions in cellular communication?
A: They facilitate communication between cells, enabling the exchange of nutrients and waste, and supporting the rapid spread of nerve and muscle impulses.
Q: Where are gap junctions particularly important, and why?
A: They are important in areas like the lens and cornea of the eye where there are no blood vessels, and for coordinated activities in the heart, nervous system, gastrointestinal tract, and uterus.
Q: How do gap junctions function in embryo development?
A: They help transfer signals that control growth and differentiation, aiding in embryonic development.
Q: What is simple epithelium?
A: A single layer of cells involved in diffusion, filtration, secretion, or absorption.
Q: What are squamous cells and their function?
A: Flat and thin cells that allow rapid passage of substances.
Q: What is stratified epithelium?
A: Multiple layers of cells providing protection in areas of high wear and tear.
Q: What is pseudostratified epithelium?
A: It looks like multiple layers due to varying nucleus levels but is actually a single layer. Some of these cells may have cilia or secrete mucus.
Q: Describe cuboidal cells and their function.
A: Cube-shaped cells, as tall as they are wide, often with microvilli, involved in secretion or absorption.
Q: What are columnar cells and their specialized features?
A: Tall, column-shaped cells providing protection, possibly having cilia or microvilli, and specialized for secretion and absorption.
Q: What are transitional cells?
A: Cells that can change shape from squamous to cuboidal as organs like the bladder stretch and contract.
Q: What are the two main types of epithelial tissue?
A: Surface epithelium and glandular epithelium.
Q: What is the function of surface epithelium?
A: It covers the body’s external surfaces, lines internal organs, forms the lining of body cavities, and covers systems such as the respiratory, digestive, and reproductive systems.
Q: What role does glandular epithelium play?
A: It makes up parts of glands responsible for secretion, such as the thyroid, adrenal, and sweat glands.
Q: What are the primary functions of epithelial tissue?
A: Protection, secretion, absorption, and excretion.
Q: Describe the structural elements of epithelial tissue.
A: It consists of cells arranged in continuous sheets, densely packed with minimal space, and is avascular but contains a nerve supply.
Q: How is the apical surface of epithelial tissue oriented and what is its function?
A: It faces outward towards a body surface or cavity and functions in protection and absorption.
Q: What do the lateral surfaces of epithelial cells do?
A: They connect to adjacent cells through junctions like tight junctions and desmosomes.
Q: What is the basal surface and its role?
A: The basal surface faces inward and attaches to the basement membrane, anchoring the epithelium.
Q: What is the basement membrane?
A: A thin, fibrous layer of extracellular matrix that sits between epithelial tissue and the underlying connective tissue.
Q: Why is epithelial tissue described as avascular?
A: It does not contain blood vessels but is supplied by nerves. It relies on diffusion from underlying connective tissues for nutrients.
Q: How is surface epithelium classified?
A: It is classified based on the arrangement of cells in layers and their shapes.
Q: What defines simple epithelium?
A: Simple epithelium consists of a single layer of cells and functions in processes like diffusion, osmosis, filtration, secretion, and absorption.
Q: What are the primary functions of simple epithelium?
A: It facilitates diffusion, osmosis, filtration, secretion, and absorption.
Q: What is secretion in the context of epithelial tissue?
A: The production and release of substances such as mucus, sweat, or enzymes.
Q: Define absorption in epithelial tissue.
A: The intake of fluids or other substances, like digested food from the intestinal tract.
Q: How are covering and lining epithelia further classified?
A: They are classified according to the shape of the cells and how many layers thick they are.
Q: What is pseudostratified epithelium and how does it function?
A: Pseudostratified epithelium appears to have multiple layers due to nuclei at different levels but is actually a single layer. All cells rest on the basement membrane, with some having cilia or being goblet cells that secrete mucus.
Q: What characterizes stratified epithelium?
A: Stratified epithelium consists of two or more layers of cells that provide protection for underlying tissues in areas of considerable wear and tear.
Q: Describe squamous cells and their function.
A: Squamous cells are flat and thin, allowing for the rapid passage of substances through them.
Q: What are the characteristics and functions of cuboidal cells?
A: Cuboidal cells are cube or hexagon-shaped, as tall as they are wide, and may have microvilli. They function in secretion or absorption.
Q: How do columnar cells differ in shape and function?
A: Columnar cells are much taller than they are wide, like columns, and protect underlying tissues. They may have cilia or microvilli and are often specialized for secretion and absorption.
Q: What are the main functions of connective tissue in relation to support?
A: Connective tissue binds, supports, and strengthens other tissues.
Q: How does connective tissue protect and insulate the body?
A: It shields and insulates internal organs.
Q: What role does connective tissue play in compartmentalization?
A: It separates structures, such as skeletal muscles, into compartments.
Q: How does connective tissue function as a transport system?
A: Blood, a connective tissue, serves as the body’s main transport system.
Q: Why is connective tissue important for blood vessel distribution?
A: It houses and distributes most blood vessels throughout the body.
Q: What is the role of connective tissue in energy storage?
A: Connective tissue stores energy reserves, such as in adipose (fat) tissue.
Q: How does connective tissue contribute to immune responses?
A: It serves as a primary site for immune function, aiding in the body’s defense.
